1. Technical Field
The present invention relates in general to telecommunications systems such as television and cable television (CATV) broadcasting. It more particularly relates to a method and apparatus for an efficient video broadcasting and teleconferencing system, and a camera and monitor used with this teleconferencing system.
2. Background Information
I. TELECONFERENCING
Conventional Television and TV cable broadcasting is generally carried out on a real-time basis. For instance, it takes the same length of time to broadcast or transmit a TV program as it does to receive and display the program. Such a broadcasting method has proven to be less than completely desirable due to limited TV bandwidth and channels allocation therein.
Channel availability has been a crucial limitation in the broadcasting industry. Channel allocation has been very valuable and expensive. It has precluded several interested persons, small businesses, consumers and local community chapters from accessing the TV broadcasting networks.
TV broadcasting has become the single most important and popular means for accessing and educating large numbers of citizens. Therefore, TV broadcasting has a direct effect on the right to free speech and expression as guaranteed by several constitutions around the world, including that of the United States of America.
Research and development has been carried out in the TV and video broadcasting field. The following patents exemplify the state of the art in the relevant field:
1. U.S. Pat. No. 4,215,369 by Ijima, entitled "Digital Transmission System for Television Video Signals", and assigned to Nippon Electric Co. PA1 2. U.S. Pat. No. 4,300,161 by Haskell, entitled "Time Compression Multiplexing of Video Signals", and assigned to Bell Telephone Laboratories, Incorporated. PA1 3. U.S. Pat. No. 4,410,980 by Takasaki, entitled "Time Division Multiplexing System", and assigned to Hitachi, Ltd. PA1 4. U.S. Pat. No. 4,533,936 by Tiemann, entitled "System for Encoding and Decoding Video Signals", and assigned to General Electric Co. PA1 5. U.S. Pat. No. 4,593,318 by Eng, entitled "Technique for the Time Compression Multiplexing of Three Television Signals", and assigned to AT&T Bell Laboratories. PA1 6. U.S. Pat. No. 4,646,135 by Eichelberger, entitled "System for Allowing Two Television Programs Simultaneously to Use the Normal Bandwidth for One Program by Chrominance Time Compression and Luminance Bandwidth Reduction", and assigned to General Electric Co. PA1 1. AD-A206 140, entitled "Investigation of Optional Compression Techniques for Dither Coding." PA1 2. AD-A210 974, entitled "Robot Vehicle Video Image Compression." PA1 3. AD-A191 577, entitled Narrative Compression Coding for a Channel with Errors." PA1 4. AD-A194 681, entitled "SNAP/DDN Interface for Information Exchange." PA1 5. AD-A174 316, entitled "A Packet Communication Network Synthesis and Analysis System." PA1 6. AD-A206 999, entitled "Geometric Methods with Application to Robust Detection and Estimation." PA1 7. AD-A207 814, entitled "Random Transform Analysis of a Probabilistic Method for Image Generation." PA1 8. AD-A188 293, entitled "A Video-Rate CCD Two-Dimensional Cosine Transform Processor." PA1 9. AD-A198 390, entitled "Navy Satellite Communications in the Hellenic Environment." PA1 1. Efficient and economic distribution of othrewise conventional printed publications; PA1 2. Promote the First Amendment constitutional freedom of speech; PA1 3. Eliminate waste of natural resources; PA1 4. Eliminate environmental problems; PA1 5. Provide ultimate substitute for otherwise conventional printed publications by:
The United States Department of Defense has sponsored several projects relating to the field of the present invention. The following Defense Technical Information Center (DTIC) technical reports exemplify some of these projects:
Therefore, it would be highly desirable to have a new and improved method and apparatus for video teleconferencing and for increasing video channel availability and for rendering the video channel allocation process more efficient. The new method and apparatus should be relatively simple and inexpensive to implement and to place into effect. The new method and apparatus should also be capable of being implemented with new, as well as existing television or receiver sets.
II. VIDEO CAMERAS
The first generation of color studio cameras used three image orthicon tubes, which were essentially three identical monochrome camera channels with provisions for superposing the three output-signal rasters mechanically and electrically. The optical system consisted of a taking lens which was part of a four-lens assembly. The scene was imaged in the plane of a field lens using a 1.6-inch diagonal image format. The real image in the field lens was viewed by a back-to-back relay lens assembly of approximately 9 inch focal length. At the rear conjugate distance of the optical relay was placed a dichromic-prism beam splitter with color-trim filters.
In this manner, the red, blue, and green components of the screen lens were imaged on the photo-cathodes of the three image orthicon tubes. A remotely controlled iris located between the two relay-lens elements was used to adjust the exposure of the image orticons. This iris was the only control required in studio operation. These cameras are no longer in use because of their size, cost, operating and setup requirements, compared to photoconductive cameras.
Four-tube (luminance-channel) cameras were then introduced when color receivers served a small fraction of the audience. The viewer of color program in monochrome became aware of lack of sharpness. Using a high-resolution luminance channel to provide the brightness component in conjunction with three chrominance channels for the Red (R), Green (G) and Blue (B) components produced images that were sharp and independent of registry errors.
Improvements in scanning components and circuits have eliminated the need for use of a separate luminance channel in order to obtain adequate resolution. However, for a period of time, the four-tube approach continued to be used for telelcine applications where the inclusion of an additional vidicon channel was not an appreciable cost consideration or of mechanical complexity. Nevertheless, the four-tube cameras were supplanted by the three-tube photoconductive cameras and by non-storage flying-spot and charge coupled device scanning systems.
A color television camera must produce R, G and B video signals which complement the characteristics of the NTSC three-gun three-phosphor standard additive display tube. For both live and film cameras it is now common to use a camera with three photoconductive pickup tubes with a high-efficiency dichromic light splitter to divide the optical image from a zoom lens into three images of red, blue and green, with different spectral characteristics.
Light splitting is accomplished by a prism or by a relay lens and dichromic system. The prism has the advantage of small size and high optical efficiency but a disadvantage in that the three tubes are not parallel to each other and are thus more susceptible to misregistration produced by external magnetic fields. A more serious problem is that of obtaining a uniform bias light on the face of the tubes. Bias light producing 2 to 10 percent of the signal is used in most modern cameras to reduce lag effects. Nonuniformity of the bias light can produce color shading in dark areas of the picture. Most new designs now use the prism splitter.
Therefore, it would be highly desirable to have a new video camera that does not use multiple color optical splitters, and which improves the sharpness and resolution of the image.
One of the most important criteria for determining the picture quality of a color television camera is the signal-to-noise ratio, which is measured in decibels according to the following formula: EQU dB=20.log[peak-to-peak video voltage / rms noise voltage].
Noise also plays an important role in the quality of the video signals transmitted. Several types of radio noise must be considered in any design, though, in general, one type will be the dominant factor. In broad categories, the noise can be divided into two types: noise internal to the receiving system, and noise external to the receiving antenna.
The noise of the receiving system is often the controlling noise in systems operating above 100 MHz. This type of noise is due to antenna losses, transmission-line losses, and the circuit noise of the receiver itself.
Several costly designs, using elaborate mathematical equations, have been devised to reduce the noise factor and to improve the signal-to-noise ratio. However, low-cost circuit designs still include a relatively low signal-to-noise ratio, for cost effectiveness.
Therefore, it is desirable to have a new circuit design and method for improving signal-to-noise ratio in video broadcasting systems, and particularly in low cost video cameras and broadcasting systems.
III. LCD MONITORS
Liquid crystal display (LCD) monitors have become increasingly popular in the television and computer industries. In general, a conventional LCD monitor includes a single rigid screen which permits the display of either video signals or computer generated signals.
U.S. Pat. No. 4,874,227 issued to Matsukawa et al. describes a large-size crystal display which is used as a large picture display for a sign or advertisement at railway stations, airports or for projection at halls or theaters. Matsukawa teaches the use of a single unitary rigid large size display of fixed dimensions and size.
U.S. Pat. No. 4,806,922 issued to McLaughlin et al. generally describes a large size LCD having several nematic curvilinearly aligned phases (NCAP) liquid crystal material. The modules are positioned adjacent to one another to effect a single display having a relatively large area. The McLaughlin patent is incorporated herein by reference.
U.S. Pat. No. 4,597,058 issued to Joseph et al. discloses a large liquid crystal display electronic sign which employs several modules that are juxtaposed adjacent to one another on a transparent diffuser plate and a conducive liquid crystal coating layer between the plates.
Liquid crystals are also defined in several publications, among which is the "Electronics Engineers' Handbook", Third Edition, McGraw Hill Publications, page 6-36, where a general brief explanation of the use of liquid crystal displays in television, is given at page 20-120.
However, conventional liquid crystal monitors still include a single screen which does not enable the user to select the desired sizes and shapes of the screen. The size and weight of a LCD monitor are important features for the LCD to compete with other displays, and printed publications such as newspapers. For this purpose, the monitor should be small in size and light in weight. Additionally, conventional displays, including lap top computers, are generally inconvenient to transport, since the screen is a single rigid screen which commonly folds over the keyboard.
Furthermore, conventional displays do not generally address the growing elderly and disabled populace, who would be very inconvenienced by the fixed size of the conventional display monitors. At present, these monitors do not enable this group of people to accommodate the displayed material to their own personal needs. In some instances, an elderly person might wish to read a newspaper, but is prevented from doing so because of that person's inability to read small print characters, and to hold and flip through the relatively heavy paper.
Therefore, it would be desirable to have a display monitor which uses liquid crystal material, and which could be sized and dimensioned by the user according to the user's particular needs.
IV. PAPERLESS NETWORK
At present, information is widely spread and distributed by means of publications such as newspapers, books and magazines. Generally, publications are distributed individually to subscribers in a relatively cumbersome , costly and inefficient way. Furthermore, the reader or subscriber usually finds it bulky, cumbersome and inconvenient to carry or transport the printer publication for reading or reviewing it at a later time.
Printed publications can be relatively heavy, and can contain information that is not of particular interest to the reader. Additionally, there is a private and public concern with respect to the manner of disposing of the printed publications once they have been read, and are no longer of use. This constitutes substantial waste of resources, which has instigated attempts to recycle and reuse the paper. Nonetheless, the recycling process does not solve all the foregoing problems.
Some methods have been designed to substitute for the paper dissemination of information, among which are computers, audio and video cassettes, floppy disks and like devices. However, there has been no paperless device or method which substitutes entirely for the paper dissemination of information.
Therefore, there is a substantial need for a new and improved paperless network and method of using the same for disseminating information. The new network and method of using it should substantially reduce or substitute for the use of paper, thus reducing the cost of distribution and waste. The new network should render the transfer, transport, storage and review of published information convenient, and should permit a wasteless disposition thereof.
U.S. Pat. No. 4,597,058, issued to Izumi et al., and U.S. Pat. No. 4,654,799, issued to Ogaki et al. describe software vending machines, it being understood the "software" includes machine readable codes to the exclusion of "human readable" or printed publications.
Software vending machines address distinctly different problems than printed publications. The Izumi vending machine provides for a cartridge programming system and method for storing a library of programs and for loading a selected program or set of programs onto reprogrammable cartridge memories.
Other objects of the Izumi vending machine are to provide a method of maintaining a program library without requiring a large inventory of memory cartridges; and to provide a system for programming a cartridge memory without removing the semiconductor memory chip from the cartridge.
However, conventional software and other publications vending machines do not yet present an acceptable alternative to printed publications, which deal with different problems, among which are: (1) Inefficient and wasteful distribution of printed publications; (2) Indirect restraint on the United States constitutional freedom of speech; (3) Waste of natural resources; and (4) Environmental concerns.
With the foreseeable depletion of natural resources, such as timber, paper publications will become increasingly expensive to produce. This will eventually force the conventional printing industry to select alternate less expensive routes. After printing, the conventional paper publications are conventionally transported, stored, and distributed at an enormous and wasteful overhead, cost and labor.
Nowadays, small businesses and individuals find it quite prohibitive to advertise and/or to express their views in conventional publications, such as newspapers. As the cost of printed publications rises with the continuing decrease of natural resources, it will become even more forbidding for individuals and small businesses to retain, even the limited access to printed publications, they now enjoy. This problem will become a major concern in the near future, as it will very subtly become an indirect restraint on the constitutional freedom of speech.
Enormous and unsubstantiated waste of natural resources are presently generated by the use of conventional paper publications. For instance, it is highly unlikely that the subscribers read each and every line or page of their daily newspapers or weekly journals. Despite the huge waste of natural resources, conventional publications methods are still being used to publish newspapers which are not even read in their entirety.
Consider also the environmental issues relating to the waste generated by the conventional paper publications. Recycling is becoming increasingly popular in industrialized countries such as the United States, and other countries are following suit. Recycling bins dedicated to paper are sprouting nationwide, and dumping sites are filling up and becoming harder to locate due to increasing social and environmental pressures.
Therefore, it would be highly desirable to have a new system which will ultimately substitute for the conventional printed publications, and which will render the distribution and dissemination of information efficient and economical, and as such, more accessible to the members of the general public. The new system should eliminate or substantially reduce the current impermissible waste of natural resources which are depleted by the conventional publication industry.